In a conventional terrestrial mobile communication system, only handover in the same system is considered among various handover cases. Thus, a handover method is designed in consideration of a case in which a user having a mobile communication terminal moves between cells of the same system or between sectors in one cell. Thus, observing received signal powers from base stations or sectors, handover is performed when the received signal power of a base station or sector is higher than that of a currently communicating base station or sector. Lately, various communication systems, such as Institute of Electrical and Electronics Engineers (IEEE) 802.11a/b/g wireless Local Area Network (LAN), Wireless Broadband (WiBro), third generation mobile communication, etc., coexist with each other, which require handover technology between different systems as well as conventional handover technology within the same system. Therefore, standardization for handover between different systems, such as media independent handover of IEEE 802.21, is also in progress.
When handover is performed between a terrestrial communication system and a satellite communication system, a much longer signaling delay occurs than in conventional handover between terrestrial communication systems. Therefore, a successful packet transfer rate may be reduced due to packet transfer delay or irregular packet transfer in data communication using Transmission Control Protocol (TCP), and momentary call drop, etc. may occur in voice communication.
The present invention is for preventing the above problems that may be caused when handover is performed between a terrestrial communication system and a satellite communication system.